This application claims benefit of Japanese Application No. 2001-195131 filed on Jun. 27, 2001, the contents of which are incorporated by this reference.
1. Field of the Invention
The present invention relates to an endoscope provided with a pliable tube composed of an integument layer formed from a resin and a metal tube integrally fitted into this integument layer in an insertion portion, and a manufacturing method therefor.
2. Description of Related Art
Hitherto, medical endoscopes have been used widely, wherein organs in body cavities, etc., can be observed by inserting slender insertion portions in the body cavities and, if necessary, various therapeutic treatments can be performed using endo-therapy products inserted through endo-therapy product channels.
In particular, regarding the endoscope used in a medical field, by inserting the insertion portion in the body cavity, observation of organs, etc., is performed and various therapies and treatments are performed using endo-therapy products inserted through the endo-therapy product channel of the endoscope. Consequently, when an endoscope and endo-therapy product used once have been reused for other patients, it has been necessary to perform cleaning and disinfection after an inspection and treatment has been completed for reasons of necessity to prevent cross infection between patients through the endoscope and endo-therapy product.
In recent years, inexpensive autoclave sterilization (high-pressure steam sterilization) has become the mainstream of the disinfection and sterilization treatments of medical equipment, wherein no complicated operation attends, it is possible to use immediately after sterilization, and a running cost is low.
However, when the step of high-pressure steam sterilization was performed repeatedly over the long term, the resin forming the integument of the pliable tube became in the condition of being likely to deform due to the thermal load, and sometimes, it was feared that the inner diameter of the pliable tube shrank during the pressurizing step in the high-pressure steam sterilization step.
When the integument formed into nearly the shape of a tube or the helical tube and mesh-shaped tube fitted into this integument are formed while being applied with a stress in the direction of diameter increase, that is, while being pulled in the direction of diameter increase, during manufacture, the inner diameter of the pliable tube may contract due to contraction of the diameter of the helical tube or mesh-shaped tube. If the inner diameter dimension of the pliable tube contract, it is feared that the built-in light guide, electric cables, and pipeline tubes will be oppressed and inconvenience, for example, breakage, will be brought about.
The present invention was made in consideration of the aforementioned circumstances. Accordingly, it is an object of the present invention to provide an endoscope in which even when high-pressure steam sterilization is performed repeatedly, occurrence of inconvenience of built-in materials due to the inner diameter of the pliable tube being changed in the direction of contraction is prevented, that is, the inner diameter dimension of the pliable tube remains in the condition as it is, or the diameter becomes in the condition of being increased.
An endoscope according to the present invention is an endoscope provided with a pliable tube composed of an integument layer formed from a resin and a metal tube integrally fitted into this integument layer in an insertion portion, and the inner diameter dimension of the aforementioned pliable tube at ambient temperature after application of the thermal load of the high-pressure steam sterilization step is larger than the inner diameter dimension at ambient temperature before application of the thermal load.
According to this configuration, a force in the direction of diameter increase is always exerted during high-pressure steam sterilization and, therefore, it can be prevented with reliability that the inner diameter of the pliable tube becomes equivalent to or less than the inner diameter dimension at ambient temperature. The above and other objects, features and advantages of the invention will become more clearly understood from the following description referring to the accompanying drawings.